Re: crossbuild fails in modpost

[Adrian Bunk <bunk@kernel.org>]

On Thu, May 15, 2008 at 09:19:26PM +0200, Jiri Slaby wrote:
> Sam Ravnborg napsal(a):
>> On Thu, May 15, 2008 at 07:35:39PM +0200, Sam Ravnborg wrote:
>>> On Thu, May 15, 2008 at 07:12:34PM +0200, Jiri Slaby wrote:
>>>> Well, let's fix sam's email.
>>>>
>>>> Jiri Slaby napsal(a):
>>>>> Hi,
>>>>>
>>>>> probably
>>>>> 4ce6efed48d736e3384c39ff87bda723e1f8e041
>>>>> kbuild: soften modpost checks when doing cross builds
>>>>>
>>>>> causes build failures on x86_64 kernel build on 32 bit machine:
>>>>>
>>>>> make -f /local/xslaby/hid/scripts/Makefile.modpost
>>>>> YYYYYYYYYYYYYY x86_64 x86_64
>>>>>  scripts/mod/modpost -m -a -o /local/xslaby/buhid/Module.symvers  
>>>>>   -S -K /local/xslaby/buhid/Module.markers -M  
>>>>> /local/xslaby/buhid/Module.markers   -s
>>>>> XXXXXXXXXXXXXXXXXX 20: 0 (2), 4 (4), 8 (4), 12 (8)
>>>>> FATAL: drivers/hid/hid-apple: sizeof(struct hid_device_id)=20 is 
>>>>> not a modulo of the size of section __mod_hid_device_table=648.
>>>>> Fix definition of struct hid_device_id in mod_devicetable.h
>>>>> make[2]: *** [__modpost] Error 1
>>>>> make[1]: *** [modules] Error 2
>>>>> make: *** [sub-make] Error 2
>>>>>
>>>>> after sticking echo into:
>>>>> __modpost: $(modules:.ko=.o) FORCE
>>>>> +       @echo YYYYYYYYYYYYYY $(KBUILD_BUILDHOST) $(ARCH)
>>>>>        $(call cmd,modpost) $(wildcard vmlinux) $(filter-out FORCE,$^)
>>>>>
>>> Your machine claims it is a x86_64 and you are building for a x86_64
>>> according to the following line:
>>>>> YYYYYYYYYYYYYY x86_64 x86_64
>>> So it looks to me that you are building for 64 bit on a 64 bit machine.
>>> So when you write:
>>>  on x86_64 kernel build on 32 bit machine:
>>>
>>> I assume you try to say that your HOSTCC is 32 bit and your
>>> kernel cc is 64 bit (or something similar).
>>>
>>> The commit you reference loosen up the check so we do not do the
>>> check if we _know_ that the host and the target system differs.
>>> The only thing I can imagine right now to solve your issue would
>>> be to skip the check if we do not use the same gcc for target and host?
>
> Well, the compiler is the same, but it's told to compile the kernel with  
> -m64. It runs on x86_64 kernel and i386 userspace. It's debian i386 gcc  
> package which understands x86_64 objects too. No SUBARCH option, it seems 
> to default to x86_64.
>...

Unless you manually fiddle with ARCH you can only build a kernel with 
the same 32<->64bit setting as your currently running kernel (no matter 
which userspace you use)...

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed